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【范围】
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1.1 Scope: T h is Aerospace Recommended Practice i s intended as a gu ide toward
standard practices for the determination of surface cleanliness that are
applicable to field operation. Some of these methods can also be used to
determine quality assurance that a surface has been properly prepared and
maintained.
The instrumental methods are: Wettability, Surface Potential Difference
(SPD) , Ell i psometry, and Optically Stimulated Electron Emission (O SEE ) .
Each instrument is described with respect to measurement techniques,
limitations, and advantages and types of available instruments. Elementary
theoretical principles and examples of the use of each instrument are also
given.
1.2 Application: The application of the instruments recommended here is to
establish that the state, or quality, of a surface is satisfactory for its
intended use. Surface cleanliness refers to the absence of materials that
would degrade the surface with respect to its intended use. In the case of
adhesive bonding, the contamination is usually organic oils or greases; for
soldering, welding, coating, or plating, it may be oxide or hydroxide films;
for painting it may be water condensate. For example, for adhesive bonding,
a properly prepared metal surface may require a hydroxide film that is
stable with respect to heat and moisture. The presence of an oxide or
hydroxide film that is not stable to heat and moisture, or that is
mechanically weak, would be considered a contaminant.
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